[BitTorrent] How BitTorrent deals with people behind NAT?

Brian Dessent brian at dessent.net
Wed Mar 2 00:27:35 EST 2005

sytelus wrote:

> Scenario #1
> My computer is behind NAT but I can see in my BitTorrent client that
> other people are indeed connecting to me and data is being uploaded
> from my machine. Because I'm behind the NAT I'd assumed that no one
> can connect to me unless I make the connection request first to those
> other users (even if I've a socket listenig). Now, is it correct for
> me to assume that those other users downloading from me are not behind
> the NAT and all of them accepts incoming connection? How this is working?
> Scenario #2
> Say 100 clients are trieng to download, out of which 90 are behind
> their own NATs. Does that means none of these 90 will never
> communicate with each other and they will depend on other 10 to get
> the file? What if all 100 are behind their own NATs?

"Behind NAT with ports forwarded" == you will initiate and receive
incoming connections

"Behind NAT without ports forwarded" == you will only be able to
initiate connections to those that can recieve them (== those not behind
NAT or those behind NAT with ports forwarded)

In either case once the connection is established both will be able to
upload to the other.  So it's not a question of being able to upload,
it's question of who you are able to connect to, and forwarding ports
makes you much more connectable.


Yahoo! Groups Links

<*> To visit your group on the web, go to:

<*> To unsubscribe from this group, send an email to:
    BitTorrent-unsubscribe at yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:

More information about the BitTorrent mailing list